EP0038869A1

EP0038869A1 - Process for the preparation of 1-carbapenems, and intermediates for their preparation

Info

Publication number: EP0038869A1
Application number: EP80102338A
Authority: EP
Inventors: Burton G. Christensen; Ronald W. Ratcliffe
Original assignee: Merck and Co Inc
Current assignee: Merck and Co Inc
Priority date: 1980-04-30
Filing date: 1980-04-30
Publication date: 1981-11-04

Abstract

Processes and intermediates for the total synthesis of 1-carbapenem antibiotics (I) via intermediates (III) and (IV):

wherein R is hydrogen, a pharmaceutically acceptable ester moiety or salt cation, or a readily removable blocking group; R⁶, R⁷ and R⁸ are, inter alia, independently selected from the group consisting of hydrogen, alkyl, alkenyl, aryl and aralkyl, and X is a conventional leaving group.

Description

BACKGROUND OF THE INVENTION

This invention relates to the total synthesis of certain 1-carbapenems and their pharmaceutically acceptable salt, ester and amide derivatives which are useful as antibiotics. Such compounds may generically be represented by the following structural formula:
wherein R⁶, R⁷, and R⁶ are independently selected from the group consisting of hydrogen, substituted and unsubstituted: alkyl, alkenyl, and alkynyl, having from 1-10 carbon atoms; cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties; aryl, such as phenyl; aralkyl, aralkenyl, and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms; heteroaryl, heteroaralkyl, heterocyclyl and heterocyclylalkyl;wherein the substituent or substituents relative to the above-named radicals are selected from the group consisting of:
chloro, bromo, fluoro)
hydroxy
alkoxy, aryloxy
carbamoyloxy
carbamoyl
amino
amidino
sulfonamido
ureido
amido
carboxy
carboxylate
acyl
acyloxy
mercapto
alkyl and aryl sulfinyl
alkyl and aryl sulfonyl
cyano
azido wherein, relative to the above listed substituents on R⁶, R⁷, and R⁸, the groups R and R² are independently selected from: hydrogen, alkyl, alkenyl, and alkynyl, having from 1-10 carbon atoms; cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties; aryl, such as phenyl; aralkyl, aralkenyl, and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms; heteroaryl, heteroaralkyl, heterocyclyl and heterocyclylalkyl and wherein the hetero atom or atoms in the above-named heterocyclic moieties are selected from the group consisting of 1-4 oxygen, nitrogen or sulphur atoms and wherein the alkyl moieties associated with said heterocyclic moieties have 1-6 carbon atoms.
This invention also relates to the carboxyl derivatives of I which are antibiotics and which may be represented by the following generic structure (I) :
wherein X' is oxygen, sulphur or NR' (R^I = H or lower alkyl having 1-6 carbon atoms); and R3' is, inter alia, representatively selected from the group consisting of hydrogen, conventional blocking groups such as trialkylsilyl, acyl and the pharmaceutically acceptable salt, ester and amide moieties known in the bicyclic β-lactam antibiotic art; the definition of R3' is given in greater detail below.
Starting from an appropriately substituted 4-allylazetidinone (II), the synthesis proceeds via intermediates III and IV:

wherein R⁶ and R⁷ are as previously defined; X is a conventional leaving group and R2 is hydrogen, a pharmaceutically acceptable ester moiety or a conventional, readily removable protecting group or salt cation. For intermediates III,R²' is as defined but preferably is an ester moiety defined under R²'. R¹' is hydrogen or a readily removable protecting group such as a triorganosilyl group.
The details of the total synthesis are given below.
The final compounds prepared by the process of this invention are disclosed and claimed in the following co-pending European Patent Application Serial Number 78 101 156 filed October 16, 1978; European Patent Application Serial Number 80 102 076 filed April 18, 1980 and European Patent Application Serial Number 78 101 157 filed October 16, 1978. To the extent that the foregoing Patent Applications' describe the antibiotic utility of final compound I and to the extent that they define substituents _R ⁶, R⁷, _R ⁸, R', X' and R^3Ithey are hereby incorporated by reference.
Thus, it is an object of the present invention to provide a novel class of antibiotics which are useful in animal and human therapy and in inanimate systems. These antibiotics are.active against a broad range of pathogens which representatively include both gram positive bacteria such as S. aureus, Strep. pyogenes, and B. subtilis, and gram negative bacteria such as E. coli, Pseudomonas, Proteus morganii, Serratia, and Klebsiella. Further objects of this invention are to provide chemical processes for the preparation of such antibiotics and their non-toxic pharmaceutically acceptable salts; pharmaceutical compositions comprising such antibiotics; and to provide methods of treatment comprising administering such antibiotics and compositions when an antibiotic effect is indicated.

DETAILED DESCRIPTION OF THE INVENTION

The process of the present invention may conveniently be summarized by the following reaction diagram:

DIAGRAM I

In words relative to Diagram I, oxidation of starting material 1 (described below) is accomplished by treating 1 in a solvent such as methylene chloride, methanol, chloroform, dichloroethane, or the like, with an oxidizing agent such as ozone, or the like at a temperature of from -100° to 0°C for from 0.1 to 4 hours, followed by treating the crude product with an oxidizing agent such as m-chloroperbenzoic acid, hydrogE peroxide, peracetic acid, or the like at a temperature of from 0°C to 100°C for from 1 to 100 hours to form 2. Chirality is conveniently introduced at this stage of the synthesis. Resolution of racemic 2 can be accomplished, for example, by fractional crystallization of the carboxylate salt formed with an optically active base such as brucine, N-methylphenethylamine, N,N-dimethylphenethylamine or the like.
The addition 2 → 3 is accomplished by treating 2 with 1,1'-carbonyidimidazole, or the like, in a solvent such as tetrahydrofuran, dimethoxyethane, DML, or the like, at a temperature of from 0 to 50°C, followed by the addition of 0.5 to 3.0 equivalents of (R2'O₂CCH₂CO₂)₂Mg, at a temperature of from 0 to 50°C for from 1 to 48 hours. R is a readily removable carboxyl protecting group such as p-nitrobenzyl, benzyl, or the like. It should also be noted that R²' may be a pharmaceutically acceptable ester moiety; such ester groups are representatively mentioned below. (DMF is dimethylformamide.)
Removal of protecting group R¹' (3 →4) may be accomplished by a variety of known procedures such as hydrolysis or hydrogenation. When R2 is a triorganosilyl group (for example, [(CH₃)₃C](CH₃)₂Si-) removal is typically accomplished by acidic aqueous hydrolysis of 3 in a solvent such as methanol, ethanol, tetrahydrofuran, dioxane, DMF, or the like in the presence of an acid such as hydrochloric, sulfuric, acetic or the like at a temperature of from 0 to 100°C for from 2 to 18 hours.
It should be noted that an otherwise identical deblocking can occur on 1 or 2. Thus, when R¹'=H, the chain elongation can proceed directly from 2 to 4.
The diazo species 5 is prepared from 4 by treating 4 in a solvent such as CH₃CN, CH₂Cl₂, THF, or the like, with an azide such as p-carboxybenzene- sulfonylazide, toluenesulfonylazide, methanesulfonyl- azide, or the like, in the presence of a base such as triethylamine, pyridine, (C₂H₅)₂NH, or the like, for from 1 to 50 hours at 0-25°C.(THF is tetrahydrofuran.)
Cyclization (5→6) is accomplished by treating 5 in a solvent such as benzene, toluene, THF, or the like, at a temperature of from 50-110°C for from 1-5 hours in the presence of a catalyst such as bis (acetylacetonato)Cu(II) [Cu(acac)₂], CuSO₄, Cu powder, Rh(OAc)₂, or Pd(OAC)₂. Alternatively, the cyclization may be accomplished by irradiating 6 througn a pyrex filter (a wave length greater than 300nm) in a solvent such as benzene, CCl₄, diethylether, or the like, at a temperature of from 0-25°C for from 0.5 to 2 hours. ["OAc" = acetate.]
Establishment of leaving group X (6 → 7) is accomplished by acylating the keto ester 6 with an acylating agent R°X such as p-toluenesulfonic acid anhydride, p-nitrophenylsulfonic acid anhydride, 2,4,6-triisopropylphenylsulfonic acid anhydride, methanesulfonic acid anhydride, trifluoromethane sulfonic acid anhydride, diphenyl chlorophosphate,toluenesulfonyl chloride, p-bromophenylsulfonyl chloride, or the like_;wherein X is the corresponding leaving group such as toluene sulfonyloxy, p-nitrophenylsulfonyloxy, diphenylphosphoryl, and other leaving groups which are established by conventional procedures and are well known in the art. Typically, the above acylation to establish leaving groups X is conducted in a solvent such as methylene chloride, acetonitrile or dimethylformamide, in the presence of a base such as diisopropylethylamine, triethylamine, 4-dimethylamino-pyridine or the like at a temperature of from -20 to 40°C for from 0.1 to 5 hours.
The leaving group X of intermediate 7 can also be halogen. The halogen leaving group is established by treating 7 with a halogenating agent such as φ₃PCl₂, φ₃PBr₂, (φ)₃PBr₂, oxalyl chloride or the like in a solvent such as CH₂Cl₂, CH₃CN, THF, or the like in the presence of a base such as diisopropylethylamine, triethylamine, or 4-dimethylaminopyridine or the like. [Ø = phenyl.]
The reaction 7→ 8 is accomplished by treating 7 in a solvent such as dioxane, dimethylformamide, dimethylsulfoxide, acetonitrile, hexamethylphosphoramide, or the like in the presence of an approximately equivalent to excess of the mercaptan reagent _HSR^$,wherein R⁸ is as defined above, in the presence of a base such as sodium hydrogen carbonate, potassium carbonate, triethylamine, diisopropylethylamine, or the like at a temperature of from -40 to 25°C for from 1 to 72 hours. When R⁸ is substituted by a primary or secondary amino group, for example -CH₂CH₂NH₂, the mercaptan reagent may be represented as HSCH₂CH₂NHR°, for example; wherein R° is a readily removable N-protecting group such as p-nitrobenzyloxycarbonyl, (-C0₂PNB), o-nitrobenzyloxycarbonyl, or the like. The specifically illustrated mercaptan reagent, HSCH₂CH₂NHR°, is typically prepared by treating aminoethylmercaptan in the presence of the desired acid chloride in the presence of a base such as sodium bicarbonate, sodium hydroxide, or the like in a solvent such as aqueous diethylether, aqueous dioxane, aqueous acetone, or the like at a temperature of from 0 to 25°C for from 0.5 to 4 hours. The foregoing mercaptan reagent, _HSR⁸, and means for its protection, is simply illustrative. The class of suitable HSR^S reagents is representatively described below and in the Examples.
The final deblocking step 8→I is accomplished by conventional procedures such as solvolysis or hydrogenation. Typically 8 in a solvent such as dioxane-water-ethanol, tetrahydrofuran-aqueous dipotassium hydrogen phosphate-isopropanol or the like is treated under a hydrogen pressure of from 1 to 4 atmospheres in the presence of a hydrogenation catalyst such as palladium on charcoal, palladium hydroxide, platinum oxide, or the like at a temperature of from 0 to 50°C for from 0.25 to 4 hours to provide I. Photolysis, when R² is a group such as o-nitrobenzyl, for example, may also be used for deblocking.

Introduction of the Thia Side Chain

Relative to the foregoing description of the invention, suitable reagents HSR⁸ utilized in the transformation 7→8 are listed below. The list is arranged according to structural and functional characteristics of the thia side chain -SR⁸; annotation is provided where necessary. The thia side chain of choice is derived from the corresponding mercaptan reagent HSR⁸. When the mercaptan contains a functional group which might interfere with the intended course of reaction, the offending group is covered. For example, when a basic nitrogen group is encountered (-NHR or -NH₂, for example) it is usually protected by acylation (e.g., -C0₂PNB) and when a carboxyl group (-CO₂H) is present, it is I usually protected by esterification (e.g., PNB ester). Such protection also facilitates in the purification of products 8 by chromatographic means. (PNB is p-nitrobenzyl).
1.) Aliphatic (including carbocyclic) Mercaptans: HSR wherein R⁸ is 1-10 carbon alkyl, cycloalkyl, alkenyl, cycloalkenyl, or alkynyl; R⁸ may be branched or unbranched, Examples
2.) Substituted Aliphatic Mercaptans: HSR⁸ wherein _R ⁸ is a 1-10 carbon branched or unbranched alkyl, cycloalkyl, alkenyl, cycloalkenyl or alkynyl group substituted by one or more halo, OH, OR¹,
NH₂, NHR¹, NR¹R²,
CO₂H, CO₂R¹, CONH₂, CONHR¹, CONR¹R², CN, δR¹,
SO₂R¹, SO₂NH₂, SO₂NHR¹, SO₂NR¹R²,

wherein R¹ and R² are as previously defined relative to substituents on R8. Preferred substituents are basic nitrogen containing groups.

EXAMPLES

n = 2-4, R¹ = H,
C^H3
n=1-3 , X=O, NH, NR¹ R¹=H, CH₃
n=2-4 0
n=2-4, R¹=CH₃, CH₂CH₃, CH₂CH₂CH₃,
CH₃
n=2-4, R¹/R²-CH₃, CH₂CH₃

R¹=H, CH₃,

n=₃-5

n=1-3, R²=H, CH₃, R¹=H, CH₃
3.) Aryl Mercaptans: HSR⁸ wherein R⁸ is phenyl or substituted phenyl. The substituents are independently selected from those previously defined for R⁸. Especially preferred substituents include alkyl, halo, hydroxy, alkoxy, acyloxy, acyl, carboxy, mercapto, sulfinyl, sulfonyl, amino, substituted amino, aminoalkyl, substituted aminoalkyl, amido, and ureido.
n= 1, 2 or 3, X= F, Cl, Br, OH, OR, OCR¹, NH₂, NHR¹, NR¹R², CH₂NH₂, CH₂NR¹R², CO₂H, CO₂R¹ COR¹, CONH₂, CONR¹R², R¹CONH, CO₂R¹, COR¹, CONH₂, CONR¹R², R¹CONH, R¹NHCONH, SR¹, SR¹, SO₂R¹, CH₃, CF₃; R¹ and R² are as previously defined under R⁸.

Examples

4.) Heteroaryl Mercaptans: HSR⁸ wherein R⁸ is a substitu unsubstituted heteroaryl group containing 1-4 O, N or S atoms. Typical substituents include those mentioned above under "Aryl Mercaptans".

Examples

X=N,O Y=H X=_S Y=H, Cl, OCH₂CH₃

R=H, CH₃

X=NH,
5.) Arylaliphatic Mercaptans: HSR8 where R⁸ is a 1-6 carbon branched or unbranched alkyl, cycloalkyl, alkenyl, or alkynyl group substituted by a phenyl or substituted phenyl group. Typical phenyl substituents include those mentioned under "Aryl Mercaptans".

Examples

6.) Heteroarylaliphatic and Heterocyclicaliphatic Mercapt

HSR⁸ wherein R⁸is a 1-6 carbon branched or unbranched alkyl, cycloalkyl, alkenyl, or alkynyl group substituted by a heteroaryl or heterocyclic group containing 1-4, O, _N, or S atoms. The heteroaryl or heterocyclic group is unsubstituted or substituted by those substituents mentioned under "Aryl Mercaptans", (No.3, above).

Examples

n=₁,₂

R¹= OCH₂CH₃

X= 0, S, NH
X = 0, S, NH
X = O, S, NH
X - 0, S, NH
x ₌ O, S, NH

R¹ = H, ^CH ₃

X = O, NH, ^NCH ₃
R¹ = CH₃
R¹ = H, CH₃
R¹ = H, ^CH ₃
R¹ = H, CH₃
R¹ = H, CH₃
R¹ = H, CH₃
n=1-3, m=1-3
R² = H, CH₃, R¹ = H, CH₃, NH₂
R¹ = H, CH₃
R¹ = H, CH₃
7.) Alkyl-Heteroatom-Alkyl Mercaptans, HSR⁸ Wherein R⁸ is -(CH₂)_nX(CH₂)_mR⁹ wherein n = 2 to 4, m = 2 to 4; X is NR°, 0 or S; and wherein R° is H, CH₃, CH₂CH₃, CH₂CH₂OH, or CH₂CH₂NH₂ and R⁹ is OH, NH₂, NHCH₃, N(CH₃)₂, O
CH₃, NH
CH₃. Note, in the above representation, the methylene carbons may be branched; for example:
and the like.
The following HSR⁸ are representative of this class:

PREPARATION OF THE SUBSTITUTED 4-ALLYLAZETIDINONE, 1

Starting material 1 is conveniently prepared from 4-allylazetidinone according to the following scheme:

SCHEME I

It should be noted that starting material la is known. Further, in this regard, co-pending, commonly assigned U.S. Patent Application Serial Number 59,₈₄₂ filed 7/23/79, is incorporated herein by reference for its definition and utilization of starting material la. R is a removable blocking group such as triorganosilyl, for example, trimethylsilyl, t-butyldimethylsilyl, triphenylsilyl, and the like.
In words relative to the above reaction diagram starting material la can be mono-, or dialkylated at ring position 3. Alkylation of la provides b. Typically, la is treated with a strong base such as lithium diisopropylamide, lithium 2,2,6,6-tetramethylpiperidide, potassium hydride, lithium hexamethyldisilazane, phenyllithium or the like in a solvent such as tetrahydrofuran (THF), hexamethylphosphoramide, ether, dimethoxyethane, and the like at a temperature of from -80°C to 0°C whereupon the alkylating agent of choice, R⁶X° is added (X° is chloro, iodo or bromo); alternatively the alkylating agent may be R^6-tosylate, _R ^6-mesylate or an aldehyde or ketone such as acetaldehyde to provide monoalkylated species lb. When desired, dialkylated species 1 may be obtained from 1b by repeating the alkylating procedures 1a→1b. The 6-substituents can also be established by direct acylation using an acylating agent such as N-acyl imidazole or the like. Such N-acyl imidazole acylating reagents are listed below. Also given below is a detailed description of this second approach for establishing, R⁶ and R⁷. The following list is representative of useful alkylating agents for establishing R⁶ and _R ⁷, according to the above scheme: 1a→1b→1: Alkylating Agents

φ = phenyl

R = CH₃, benzyl, p-nitrobenzyl

R = CH₃, benzyl, p-nitrobenzyl

R = protecting group

R is removable carboxyl protecting group, such as benzyl.
As mentioned above, the 6-substituents may also be established by acylation. Utilization of such acylating agents may be demonstrated in the following manner with regard to a preferred starting material 1:
wherein R⁷ and R^1' are as defined above. R^6' is defined relative to the definition of R⁶and in that sense is the balance of the previously identified group R6. In other words, for purposes of this definition R6'CH(OH)- = R⁶. An especially preferred material 1 is when R⁷ is hydrogen and R⁶' is methyl. Such preferred starting materials are described in the following co-pending, commonly assigned U.S. Patent Application Serial Number 59,842 filed July 23, 1979 which is incorporated herein by reference. Basically, such I'-hydroxy R⁶' species 1 are prepared according to the following scheme: SCHEME II
The alkylation 1a→1, Scheme II, is accomplished as previously described, by treating 1a in a solvent such as tetrahydrofuran, dimethoxyethane, diethylether, hexamethylphosphoramide, at a temperature of from -100° to -20°C with a strong base such as lithium diisopropylamide, lithium hexamethyldisilazide, lithium 2,2,6,6-tetramethylpiperidide, potassium hydride or the like followed by the addition of an equivalent to 10 fold excess of an aldehyde. This reaction gives a mixture of isomers from which the desired trans-R form 1 can be conveniently separated by chromatography or crystallization.
Intermediate la may proceed directly to 1 as indicated above, or it may take the circuitous path via 1'. The direct acylation, to 1' is accomplished by treating 1a with two or more equivalents of a base such as lithium diisopropylamide, lithium hexamethyldisilazide, lithium 2,2,6,6-tetramethylpiperidide, in a solvent such as tetrahydrofuran, diethylether, or dimethoxyethane, for example, at a temperature of from -100 to -20°C with an acylating agent such as N-acyl imidazole or the like. Addition of the-la plus base mixture to the acylating agent is preferred.
Representative acylating agents for this scheme 1a→1'→1 are listed below.
Further with respect to Scheme II, the reduction, 1'→1 is accomplished by contacting the ketone with a reducing agent such as potassium tri(sec-butyl)borohydride, lithium tri(sec-butyl)borohydride, sodium bprohydride, sodium tris(methoxyethoxy)aluminum hydride, lithium aluminum hydride or the like in a solvent such as diethylether, tetrahydrofuran, toluene or the like at a temperature of from -78° to 25°_C. The reaction can conveniently be conducted in the presence of an added complexing salt such as potassium iodide, magnesium bromide or the like.
In a similar manner, unresolved 1 (cis and trans) may be oxidized to 1' for reduction to 1 as indicated above:
The oxidation is accomplished with an oxidizing agent such as dipyridine chromium (VI) oxide, trifluoroacetic anhydride-dimethylsulfoxide-triethylamine, pyridinium dichromate, acetic anhydride-dimethylsulfoxide in a solvent such as methylene chloride, acetonitrile, or the like at a temperature of from -78 to 25°C for from 5 minutes to 5 hours.
As noted above, the compounds of the present invention may also generally be represented by the following structural formula:
wherein X¹ is oxygen, sulfur or NR' (R'is hydrogen or loweralkyl having from 1 to 6 carbon atoms); and R³¹ is hydrogen, or, inter alia, is representatively selected to provide the pharmaceutically acceptable salt, ester anhydride (R^3' is acyl) and amide moieties known in the bicyclic β-lactam antibiotic art; R^3' may also be a readily removable blocking group. Identification of the Radical -COX'R^3'
In the generic representation of the compounds of the present invention (I, above), the radical represented by -COX'R^3' .is, inter alia, -COOH (X' is oxygen and R^3' is hydrogen) and all radicals known to be effective as pharmaceutically acceptable ester, anhydride (R^3' is acyl) and amide radicals in the bicyclic β-lactam antibiotic art, such as the cephalosporins and penicillins and nuclear analogues thereof.
Suitable blocking esters [R^3', X' = O) include those selected from the following list which is representative:

(i) R^3'= CR^aR^bR^c wherein at least one of R^a, Rand R^c is an electron-donor, e.g., p-methoxyphenyl. The re- _mai_ni_ng _R ^a, R^b and R^c groups may be hydrogen or organic substituting groups. Suitable ester groups of this type include p-methoxybenzyloyxcarbonyl.
(ii) R^3' = CR^aR^bR^c wherein at least one of R^a, R^b and R^c is an electron-attracting group, e.g., p-nitrophenyl, trichloromethyl, and o-nitrophenyl. Suitable esters of this type include p-nitrobenzyloxycarbonyl, and 2,2,2-trichloroethoxycarbonyl.
(iii) R^3' = CR^aR^bR^c wherein at least two of R^a, _R ^b and R^c are hydrocarbon such as alkyl, e.g., methyl or ethyl, or aryl, e.g., phenyl and the remaining R^a, R^b and R^c group, if there is one, is hydrogen. Suitable esters of this type include t-butyloxycarbonyl, diphenylmethoxycarbonyl and triphenylmethoxycarbonyl.

Silyl esters, under this category of blocking groups, may conveniently be prepared from a halosilane of the formula: R⁴ ₃SiX' wherein X' is a halogen such as chloro or bromo and R is alkyl, e.g., methyl,-ethyl, t-butyl.
Pharmaceutically acceptable carboxyl derivatives of the present invention are those derived by reacting I with alcohols, acylating reagents and the like. For example, esters and amides of interest are the above-listed starting materials and final products having the -COX'R^3' group at the 3-position; wherein X' is oxygen, sulfur or NR' (R' is H or R^3'), and R³¹ is alkyl having 1-6 carbon atoms, straight or branched, such as methyl, ethyl, t-butyl, and the like; carbonylmethyl, including phenacyl; aminoalkyl including 2-methylaminoethyl, 2-diethylaminoethyl; alkanoyloxyalkyl wherein the alkanoyloxy portion is straight or branched and has 1-6 carbon atoms and the alkylportion has 1-6 carbon atoms, such as pivaloyloxymethyl; haloalkyl wherein halo is chloro, and the alkyl portion is straight or branched having 1-6 carbon atoms, e.g., 2,2, 2-trichloroethyl; alkenyl having 1-4 carbon atoms such, as 2-propenyl, 3-butenyl, and 4-butenyl; aralkyl and lower.alkoxyl- and nitro- substituted aralkyl such as benzyl, benzhydryl, o-nitrobenzyl, p-methoxybenzyl, and p-nitrobenzyl; phthalidyl; benzyloxyalkyl having 8-10 carbon atoms such as benzyloxymethyl, and (4-nitro) benzyloxymethyl.
In addition to the esters (and thio esters) listed above, amides are also embraced by the present invention, i.e., wherein X' is the -N- group. Representative of such amides are those wherein R' is selected from the group consisting of hydrogen and lower alkyl such as methyl and ethyl.
The most preferred -COX' R^3' radicals of the present invention are those wherein (relative to Structure I above), X' is oxygen and R^3' is hydrogen; loweralkyl having 1-4 carbon atoms; lower alkenyl such as 3-methylbutenyl, 4-butenyl and the like; benzyl and substituted benzyl such as p-nitrobenzyl; pivaloyloxymethyl, 3-phthalidyl; and phenacyl.
The compounds of the present invention (I) are valuable antibiotics active against various gram-positive and gram-negative bacteria and accordingly.find utility in human and veterinary medicine. Representative pathogens which are sensitive to antibiotics I include: _Staphyloccus aureus, Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, Salmonella typhosa, ^psuedomonas and Bacterium proteus. The antibacterials of the invention are not limited to utility as medicaments; they may be used in all manner of industry, for example: additives to animal feed, preservation of food, disinfectants, and in other industrial systems where control of bacterial growth is desired. For example, they may be employed in aqueous compositions in concentrations ranging from 0.1 to 100 parts of antibiotic per million parts of solution in order to destroy and inhibit the growth of harmful bacteria on medical and dental equipment and as bactericides in industrial applications, for example in waterbased paints and in the white water of paper mills to inhibit the growth of harmful bacteria.
The products of this invention may be used in any of a variety of pharmaceutical preparations. They may be employed in capsule, powder form, in liquid solution, or in suspension. They may be administered by a variety of means; those of principal interest include: orally, topically or parenterally by injection (intravenously or intramuscularly).
Such tablets and capsules, designed for oral administration, may be in unit dosage form, and.may contain conventional excipients, such as binding agents, for example, syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers, for example, lactose, sugar, cornstarch, calcium phosphate, sorbitol, or glycerine; lubricants, for example, magnesium stearate, talc, polyethylene glycol, silica; disintegrants, for example, potato starch; or acceptable wetting agents such as sodium lauryl sulphate. The tablets may be coated according to methods well known in the art. Oral liquid preparations may be in the form of aqueous or oily suspensions, or solutions, or they may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents, for example, sorbitol, methyl cellulose, glucose/sugar syrup, gelatin,- hydroxyethylcellulose, or carboxymethyl cellulose. Suppositories will contain conventional suppository bases, such as cocoa butter or other glycerides.
Compositions for injection, the preferred route of delivery, may be prepared in unit dosage form in ampules, cr in multidose containers. The compositions may take such forms as suspensions, solutions, or emulsions in oily or aqueous-vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient may be in powder form for reconstitution, at the time of delivery, with a suitable vehicle, such as sterile water.
-The compositions may also be prepared in suitable forms for absorption through the mucous membranes of the nose and throat or bronchial tissues and may conveniently take the form of liquid sprays or inhalants, lozenges, or throat paints. For medication of the eyes or ears, the preparation may be presented in liquid or semi-solid form. Topical applications may be formulated in hydrophobic or hydrophilic bases as ointments, creams, lotions, paints, or powders.
The dosage to be administered depends to a large extent upon the condition and size of the subject being treated as well as.the route and frequency of administration -- the parenteral route by injection being preferred for generalized infections. Such matters, however, are left to the routine discretion of the therapist according to principles df treatment well known in the antibiotic art. In general, a daily dosage consists of from about 5 to about 600 mg of active ingredient per kg. of body weight of the subject in one or more treatments per day. A preferred daily dosage for adult humans lies in the range of from about 10 to 240 mg. of active ingredient per kg. of body weight. Another factor influencing the precise dosage regimen, apart from the nature-of the infection and peculiar identity of the individual being treated, is the molecular weight of the chosen species of this invention (I).
The compositions for human delivery per unit dosage, whether liquid or solid, may contain from 0.1_% to 99% of active material, the preferred range being from about 10-60%. The composition will generally contain from about 15 mg. to about 1500 mg. of the active ingredient; however, in general, it is preferable to employ a dosage amount in the range of from about 250 mg to 1000 mg. In parenteral administration, the unit dosage is usually the pure compound I in sterile water solution or in the form of a soluble powder intended for solution. For zwitterionic species described under Structure I, the pH of such solutions typically will correspond to the zwitterionic point; however, consideration of individual properties of solubility and stability may require such aqueous solutions to have a pH other than that of the zwitterionic point, for example in the range of 5.5 to 8.2.
In the foregoing word description of the above schematic reaction diagram for the total synthesis of the defined carbapenem antibiotics, it is to be understood that there is considerable latitude in selection of precise reaction parameters. Suggestion of this latitude and its breadth is generally indicated by the enumeration of equivalent solvent systems, temperature ranges, protecting groups, and range of identities of involved reagents. Further, it is to be understood that the presentation of the synthetic scheme as comprising distinct steps in a given sequence is more in the nature of a descriptive convenience than as a necessary requirement; for one will recognize that the mechanically dissected scheme represents a unified scheme of synthesis and that certain steps, in actual practice, are capable of being merged, conducted simultaneously, or effected in a reverse sequence without materially altering the progress of synthesis.
The following examples recite a precise scheme of total synthesis. It is to be understood that the purpose of this recitation is to further illustrate the total synthesis and not to impose any limitation. Temperature is given in °C.

EXAMPLE 1

Preparation of 1-(t-Butyldimethylsilyl-4-(prop- ₂-ene)-azetidin-2-one

t-Butyldimethylchlorosilane (7.51 g, .49.8 mmol) is added in one portion to an ice-cold, stirring solution of 4-(prop-2-ene)-azetidin-2-one (5.26 g, 47.4 mmol) and triethylamine (5.04 g 49.8 mmol) in anhydrous dimethylformamide (100 ml). A voluminous white precipitate forms almost immediately. The reaction mixture is stirred at 0-5° for 1 hour and then allowed to warm to room temperature. Most of the solvent is removed under vacuum to give a residue which is partitioned between diethyl ether (250 ml) and water. The ethereal phase is washed with 2.5N hydrochloric acid (50 ml), water (3x50 ml), and brine, dried with magnesium sulfate, filtered and evaporated under vacuum to provide an oil which is purified either by vacuum distillation or chromatography on silica gel (20% ether in petroleum ether) to yield 1-(t-Butyldimethylsilyl-4-(prop-2-ene)-azetidin-2-one. n.m.r. (CnCl₃) δ 4. 8-6.0 (3H, m, olefinic),δ 3.5 (1H, m, H4), δ 3.03 (1H,dd,J=15,5.2H3x) , δ 2.56 (1H, dd,J=15, 2.8,H2β) ,δ1. 8-2. 8 (2H, m, allylic), δ 0.9 (9H,S) ,δ0.2 (6H,S).

EXAMPLE 2

1-(t-Butyldimethylsilyl)-3-(1-hydroxyethyl)-4- tprop-2-ene)-azetidin-2-one

n-Butyllithium in hexane (26.25 mmol) is added slowly by syringe to a solution of diisopropylamine (26.25 mmol) in anhydrous tetrahydrofuran (100 ml) at -78°C. The resulting solution is stirred for 15 min prior to the addition of a solution of l-(t-butyldimethylsilyl)-4-(prop-2-ene)-azetidin-2- one (25.0 mmol) in anhydrous tetrahydrofuran (25 ml). After stirring for 15 min at -78°C, acetaldehyde (75 mmol) is added by syringe and the resulting solution is stirred at -78°C for 5 min. Saturated aqueous ammonium chloride solution (15 ml) is added by syringe and the reaction mixture is allowed to warm to room temperature, then diluted with ether (250 ml) and washed with 2.5N hydrochloric acid solution (2 x 50 ml), water (100 ml) and brine and dried over magnesium sulfate. Solvents are removed in vacuo and the semi-solid residue is chromatographed on silica gel (1:1, ether:petroleum ether). The first product to elute is the cis R^*compound (688 mg) n.m.r. (CDCl₃+D₂O)δ 4.8 - 6.2 (3H, m, olefinic) , δ 4.2 (1H, dγ J= 6.5, 3.7, H-8) , δ3.75 (1H, ddd, J=5.5, 5, 4.8, H-5) δ 3.28 (H, dd, J=5.5, 3.7, H-6) ,δ 2.2-3.0 (2H, m, allyl) ,δ 1.35 (3H, d, J=6.5, CH₃-CHOH) , δ 1.0 (9H, S,±Si-) ,δ 0.3 (6H, S, (CH₃)₂Si). The second fraction is a mixture of the trans R^*and S^*products (5.56 g). Crystallization of this material from petroleum ether gives the pure trans R^* material, m.p. 81-82°C.
IR (CHCl₃) 3400, 2920, 2850, 1723 cm^-1; n.m.r. (CDCl₃ + D₂O) δ 4.9-6.2 (^{3H, m,} olefinic) ,δ 4.1 (lH, dq, J= 7.0, 6.8, H8), δ 3.66 (lH, ddd, J= 11, 4.5, 3.0, H5), δ 2.9 (1H, dd, _J=_6.8, 3.0, H6)δ 1.8-2.8 (2_H, _m, allyl ), δ 1.26 (3H, d, J=7.0, CH₃-) , δ 1.0 (9H, S, ± Si) , δ 0.28 (6H, 2S, (CH₃)₂Si).

EXAMPLE 3

(3S^*, 4R*)-1-(t-Butyldimethylsilyl)-3-(1-oxoethyl)-4-(prop⁼2-ene)-azetidin-2-one

A. Trifluoroacetic anhydride (7.5 mmol) is added dropwise by syringe to a solution of dimethylsulfoxide (10 mmol) in anhydrous methylene chloride (15 ml) at -78°C. The resulting mixture is stirred at -78°C for 20 min. during which time a white precipitate forms. A solution of 1-(t-butyldimethylsilyl)-3-(1-hydroxyethyl)-4-(prop-2-ene)-azetidin-2-one (5.0 mmol) in methylene chloride (15 ml) is added by syringe and the resulting solution is stirred at -78°C for 30 min. Triethylamine (14 mmol) is added by syringe and the cooling bath is removed. After an additional 1 hr., the reaction mixture is diluted with methylene chloride (100 ml), washed with water (50 ml) and brine and dried over magnesium sulfate. Removal of solvents in vacuo yields an oil which is chromatographed on silica gel (2:1, petroleum ehter:ether) to yield (3S*,4R*)-1-(t-butyldimethylsilyl-3-(1--oxoethyl)-4-(prop-2-ene)-azetidin-2-one. I.R. (CHCl₃) ₂₉25, 2855, 1734, 1705 cm^-1; n.m.r. (CDCl₃) δ 4.8-6.1 (3H, m, olefinic) δ 3.8-4:2 (2H, overlapping multiplets, _H5, H6), δ 2.0-2.9 (2H, m, allylic) , δ 2.3 (3H, S, CH₃-
O) γ 0.96 (9H, S, ± Si-) , δ 0.25 (6H, 2S, (CH₃)₂Si) . Mass spectrum m/e 267(m+)252,226,210.
B. n-Butyllithium in hexane (4.10 mmol) is added by syringe to a solution of diisopropylamine (4.10 mmol) in anhydrous tetrahydrofuran (16 ml) at -78°_C. The resulting solution is stirred at -78°C for 15 min. prior to the addition of a solution of l-(t-butyldimethylsilyl)-4-(prop-2-ene)-azetidin-2-one (2.0 mmol) in anhydrous tetrahydrofuran (2 ml). After an additional 15 min. at -78°C, the reaction mixture is added via a Teflon tube to a mixture of N-acetylimidazole (4.1 mmol) in anhydrous tetrahydrofuran (16 ml) at -78°C. The resulting yellow reaction mixture is stirred at -78°C for 15 min, then quenched by addition of saturated aqueous ammonium chloride solution (10 ml). The reaction mixture is diluted with ether (100 ml) and washed with 2.5N hydrochloric acid solution (25 ml) water (25 ml) and brine. The organic phase is dried over magnesium sulfate and concentrated in vacuo to yield an oil. This material is chromatographed on silica gel (2:1 petroleum ether:ether) to yield (3S*,4R*)-1-(t-butyldimethylsilyl) -3- (1-oxoethyl) -4- (prop-2-ene) - azetidin-2-one.

EXAMPLE 4

(3S*, 4R*)-1-(t-Butyldimethylsilyl)-3-[(R*)-1-hydroxyethyl]-4-(prop-2-ene) -azetidin-2-one

K-Selectride (potassium tri-(sec)-butylborohydride) in tetrahydrofuran (4.8 mmol) is added by syringe to a mixture of potassium iodide (2.0 mmol) and (3S^*, 4R*)-1-(t-butyldimethylsilyl)-3-(1-oxoethyl)-4-(prop-2-ene)-azetidin-2-one (2.0 mmol) in anhydrous ether (20 ml) at room temperature. The resulting mixture is stirred at room temperature for 2.5 hours, then quenched by addition of glacial acetic acid (9.6 mmol). The resulting mixture is diluted with ethylacetate (100 ml) and filtered through celite. Removal of solvents in vacuo gives an oil which is chromatographed on silica gel (1:1 ether:petroleum ether) to yield 1.90 g (95%) of (3S^*, 4R^*)-1-(t-Butyldimethylsilyl)-3-(1-hydroxyethyl)-4-(prop-2-ene)-azetidin-2- one as a white solid. NMR examination of this material indicates the R^*/S^* ratio at the hydroxy center to be >5/1. The R^* isomer is isolated by crystallization from petroleum ether.

EXAMPLE 5

(3S^*, 4R*) -1- (t-Butyldimethylsilyl) -3-( (R*) -1-hydroxyethyl]-4-(carboxymethyl)-azetidin-2-one

A solution of (38^*, 4R*)-1-(t-Butyldimethylsilyl)-3-[(R*)-1-hydroxyethyil-4-(prop-2-ene)-azetidin-2-one (3.0 mmol) in dry methylene chloride (30 ml) is cooled to -78°C (dry ice-acetone) and a stream of ozone is bubbled through until the reaction mixture becomes blue. The ozone flow is then stopped and the reaction is purged by bubbling through nitrogen until the blue color disappears. Solid m-chloroperbenzoic acid (3.0 mmol) is added and the cold bath is removed. When the reaction mixture reaches room temperature, the flask is fitted with a reflux condenser and the mixture is heated at reflux for three days. Removal of solvents in vacuo gives a white solid which is chromatographed on silica gel (2% glacial acetic acid in methylene chloride) to yield 663 mg (77%) of (3S^*, 4R^*)-l-(t-Butyldimethylsilyl-3-[(R^*)-l-hydroxyethyl]-4-(carboxymethyl)-azetidin-2-one. n.m.r. (CDC1₃ + D₂O) δ 3.6-4.3 (2H, m) ,δ 2.98 (1H, dd, _J=₇, 2.1) , δ 2.7 (2H, d of ABq, -CH₂CO₂H) , δ 1.29 (3H, d, J=6) , δ 0.95 (9H, S) ,δ 0.25 (6H, S).

EXAMPLE 6

(3S*, 4R*)-1-(t-Butyldimethylsilyl)-3--[(R*) -1-hydroxyethyll-4-(3-p-nitrobenzyloxycarbonyl-2- oxopropyl)-azetidin-2-one

l,l'-Carbonyldimidazole (1.10 mmol) is added in one portion to a solution of (3S* 4R*)-1-(t-butyldimethylsilyl-3-[(R*)-1-hydroxyethyl]-4-carboxymethyl-azetidin-2-one (1.0 mmol) in anhydrous tetrahydrofuran (5 ml) at room temperature. The resulting solution is stirred at room temperature for 6 hours. In a second flask, magnesium ethoxide (5 mmol) is added in one portion to a solution of the mono-p-nitrobenzyl ester of malonic acid (10 mmol) in anhydrous tetrahydrofuran (25 ml). The resulting mixture is stirred at room temperature for 1 hr, then the tetrahydrofuran is removed at the pump and the gummy residue is triturated with ether to yield the magnesium salt as an off-white solid.(1.1 mmol) of this magnesium salt is then added to the first reaction flask and the resulting mixture is stirred at room temperature for 18 hrs. The reaction mixture is then poured into 50 ml of ether, washed with 0.5N hydrochloric acid solution (20 ml), water (20 ml), saturated aqueous sodium bicarbonate solution (20 ml), brine and dried over magnesium sulfate. Removal of solvents in vacuo gives an oil which is chromatographed on silica gel (ether) to yield (3S*4R*)-1-(t-butyldimethylsilyl)-3-[(R*)-1-hydroxyethyl]-4-(3-p-nitrobenzyloxycarbonyl-2- oxopropyl)-azetidin-2-one. n.m.r. (CDCl₃- H₂O) δ 8.24, 8.10, 7.52, 7.38(2H, AB, aromatic),δ 5.26 (2H, S, -CH₂-Ar),δ 3.5-4.2 (2H, m, H-5, H-8) ,δ 2. 6-3.3 (3H, m, H-6, -CH₂-
O-), δ 1.3 (3H, d, J=6.6, CH₃-) δ 0.98 (9H, S, ± Si-) δ 0.25 (6H, S, (CH₃)₂Si
).

EXAMPLE 7

(3S*,4R*)-3- [(R*)-1-hydroxyethyl] -4- ( 3-p-nitrobenzyloxycarbonyl-2-oxopropyl-azetidin-2-one

A solution of (3S*, 4R*)-1-(t-butyldimethylsilyl)-3-[(R*)-1-hydroxyethyl]-4- (3-p-nitrobenzyloxycarbonyl-2- oxopropyl)-azetidin-2-one (1.0 mmol) in 20 ml of 9:1 (v/v) methanol-water is cooled to 0°C. Concentrated hydrochloric acid (0.34 ml) is added and the resulting solution is stirred at 0°C for 15 min., then allowed to warm to room temperature. After 2.5 hrs, at room temperature the reaction mixture is diluted with ethyl acetate (25 ml), washed with water (10-ml) and brine, dried over magnesium sulfate and concentrated in vacuo to yield (3S*; 4R*)-3- [(R*)-1-hydroxyethyl] -4-(3-p-nitrobenzyloxycarbonyl-2-oxopropyl)-azetidin-2-one.

EXAMPLE 8

Preparation of (3S*,4R*)-3-[(R*)-1-hydroxyethyl)-4-[3- (4-nitroberizyl)oxycarbonyl-2-oxo-3-diazopropyl]azetidin-2- one

Triethylamine (263 mg, 2.6 mmol) is added by syringe to a mixture 'of (3S*, 4R*)-3- [(R*)-1-hydroxyethyl] -4- [3- (4-nitrobenzyl)oxycarbonyl-2-oxopropyl]azetidin-2-one (253 mg, 0.72 mmol) and p-carboxybenzene sulfonylazide (196 mg, 0.84 mmoll in dry acetonitrile (6 ml) at 0°C. When addition is complete the cooling bath is removed and the reaction mixture is stirred at room temperature for 1 hour. The mixture is then diluted with ethyl acetate C50 ml) and filtered. The filtrate is concentrated in vacuo and the residue is chromatographed on a short silica gel column (ethyl acetate) to yield 222 mg, (81% overall from (3S*, 4R*)-1- (t-butyldimethylsilyl) -3-[(R*)-1-(t-butyl dimethylsilyloxy)ethyl]-4-[3-(4-nitrobenzyl)oxycarbonyl-2-oxopropyl]azetidin-2-one) of (3S*,4R*)-3-(R*)-1-hydroxyethyl)-4-[3-(4-nitrobenzyl)oxycarbonyl-2-oxo-3-diazopropyl]azetidin-2-one as a white solid. IR(CHCl₃, CM^-1) 3410, 2132, 1756, 1718, 1650, 1350, 1280, 1120; n.m.r.(CDCl₃) δ 7.9 (2d-aramatic,4) , δ 5.4 (s,2) , δ 6.2 (brs,1) , δ 4.1 (m,2) , δ 2. 6-3. 6 (m, 4) , δ 1. 32 (d, 3, J=6. 2) .

EXAMPLE 9

_Preparation..of (5R*,6S*)p-Nitrobenzyl 6- [(R*)1-hydroxyethyl]-1-azabicyclo [3.2.0]heptan-3,7-dione-2-carboxylate

A suspension of (3S*,4R*)-3-[(R*)-1-hydroxyethyl]-4-[3-(4-nitrobenzyl)oxycarbonyl-2-oxo-3-diazopropyl]azetidin-2-one (56.4 mg, 0.15 mmol) and rhodium (II) acetate (0.1 mgl in dry benzene (3ml) is deoxygenated by bubbling through nitrogen for 10 minutes. The mixture is then heated to 78°C for 1 hour. During heating the solid starting material gradually goes into solution. The mixture is then cooled, filtered to remove the catalyst, and the filtrate is concentrated in vacuo to yield (5R*, 6S*)p-nitrobenzyl 6-[(R*)-1-hydroxyethyl]-1-azabi- cyclo[3.2.0]heptan-3,7-dione-2-carboxylate.
PNB = p-nitrobenzyl n.m.r.: (300MHz, CDCl₃)δ8.26, 7.54 (aromatic, 4), 5.29 (AB, 2), 4.77 (s, 11, 4.32 (dg, 1, J=6.6,7), 4.16(ddd, 1, J=7,7.5, 2.2), 3.21 (dd, 1, J=7,2.2), 2.94 (dd, 1, J=19.5,7) 2.50(dd, 1, J=19.5,7.5), 2.2(brs, 1), 1.37(d, 3, J=6.6). I.R.: (CHCl₃, CM^-1) 1770, 1758, 1610, 1522, 1353

EXAMPLE 10

Preparation of p-Nitrobenzyloxycarbonylaminoethanethiol

To 600 ml diethyl ether (Et₂0) - 75 ml H₂0 in an ice bath with stirring is added 3.2 g cysteamine hydrochloride (mw = 114; 28.1 mmole). A solution of 7.14 g NaHCO₃ (mw = 84; 85 mmole) in 75 ml H₂0 is added. The ice bath is removed, and at room temperature a solution of 6.75 g p-nitrobenzylchloroformate (mw = 216; 31.3 mmole) in 270 ml Et₂0 is added dropwise over a period of one hour. After 10 additional minutes, the layers are separated. The ether layer is extracted with 150 ml 0.25 N HCl, and then with 200 ml brine. Each aqueous layer is then backwashed successively with 100 ml Et₂O. The combined Et₂0 layers are dried over anhydrous MgS0₄, filtered, and concentrated under a N₂ stream. The crystalline residue is slurried in a small amount of ether, filtered, and the pale yellow crystals are dried under high vacuum to give 4.7 g. p-nitrobenzyloxycarbonylaminoethanethiol (65% yield). NMR (CDCl₃). 8.18 (d, J=8Hz, aromatic protons ortho to nitro), 7.47 (d, J=8Hz, aromatic protons meta to nitro), 5.27 (-NH-), 5.20 (s, -CH₂-NH-), 2.67 (m, -CH₂-SH), 1.35 (t, J=8.5Hz, -SH) in ppm downfield from TMS. IR (CHCl₃ solution): carbonyl- 1725 cm^-1. M.S.: molecular ion-256, (M-47) at 209, (M-136) at 120, +CH₂φpNO₂ at 136.

EXAMPLE 11

Preparation of (5R,*,6S*)p-Nitrobenzyl 3-[2-(p-nitrobenzyloxycarbonyl)aminoethylthio]-6-[(R*)-1-hydroxyethyl]-1-azabicyclo[3.2.0]-hept-2-en-7-one-2-carboxylate

(5R*,5S*)p-Nitrobenzyl 6- [(R*)1-hydroxyethyl] -1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (51 mg, 0.147 mmol) is dissolved in acetonitrile (3 ml) and the resulting solution is cooled to 0°C. Diisopropylethylamine (22 mg, 0.17 mmol) is added by syringe and the resulting solution is stirred at 0°C for 1 minute prior to the addition of a solution of freshly recrystallized p-toluene sulfonic anhydride (51 mg, 0.156 mmol) in dry acetonitrile (1 ml). The resulting solution is stirred at 0°C for 1 hour to provide (5R*,6S*)p-nitrobenzyl 3-(p-toluenesulfonyloxy)-6-[(R*)-1-hydroxyethyl]-1-azabicyclo[3.2.0]hept-2-en-7- one-2-carboxylate, then cooled to -25°C. Diisopropylethylamine (80.5 mg, 0.624 mmol) is added by syringe followed shortly thereafter by a solution of _N-p-nitrobenzyloxycarbonylcysteamine (40 mg, 0.156 mmol) in 1 ml of dry acetonitrile. The reaction mixture is then stored in a refrigerator for 70 hrs. The mixture is diluted with 25 ml of ethylacetate washed with brine and dried over magnesium sulfate. Solvents are removed in vacuo to yield a yellow oil which is chromatographed on a silica gel plate (ethyl acetate, R_f = 0.4) to yield (5R*,6S*)-p-nitrobenzyl-3-[2-(p-nitrobenzyloxycarbonyl)-aminoethylthio]-6-[(R*)-1-hydroxyethyl]-1-azabicyclo-[3.2.0]-hept-2-en-7-dione-2-carboxylate as a yellow solid. IR (Nujol mull) 1773 and 1690 cm^-1; n.m.r. (CDCl₃)δ 7.54-8.26 (overlapping ABq, 4), δ 5.40 (ABq, 2), δ 5.22(s,2), δ4.27 (m,2), δ3.47 (m), 3.23(dd, 1), δ 3.14 (dd, 1) δ 3.40(dd, 1), δ3.04 (m, 2) 191.37 (d, 3).

EXAMPLE 12

Preparation of Thienamycin

A mixture of N-p-nitrobenzyloxycarbonyl. thienamycin p-nitrobenzyl ester (10 mg, 0.017 mmol) and 10% Pd/C-Bolhofer type in tetrahydrofuran (2 ml), 0.1M dipotassium hydrogen phosphate solution (1.4 ml) and 2-propanol (0.2 ml) is hydrogenated at 40 psi on the Parr shaker for 30 minutes. The mixture is then filtered and the catalyst is washed with water (3 x 3 ml). The combined filtrate and washings are extracted with ethyl acetate-ethyl ether then concentrated to ~3ml and lyophilized.

EXAMPLE 13

Preparation of 6-Methylthienamycin ^{* *} * 1-(t-Butyldimethylsilyl)-3-(1-hydroxyethyl)-3a, β-methyl-4-(prop-2-en)-azetidin-2-one

To 342µl diisopropylamine (2.44 mmol) in 5 ml anhydrous tetrahydrofuran (THF) at -78°C with stirring under N₂is added 1 ml of 2.45M n-butyllithium (2.45 mmol). After stirring for 10 min, a solution of 500 mg of 1-(t-butyldimethylsilyl)-4-(prop-2-en)-azetidin-2-one in 2 ml anhydrous THF is added. After stirring for 10 min, 153µl methyliodide (2.46 mmol) is added. The cooling bath is removed, and the reaction mixture is stirred for 25 min. Upon re-cooling to -78°C, 1 ml of 2.45M n-butyllithium (2.45 mmol) is added. After 5 min, 250µl distilled acetaldehyde (4.49 mmol) is added, and the cooling bath is removed. After 30 min, the reaction mixture is added to 10 ml 1M KH₂PO₄-brine-Et₂O. After separation of the layers, the organic layer is washed with 10 ml 1M KH₂PO₄-15 ml brine and then with brine. After drying over magnesium sulfate, filtration, and concentration in vacuo, 626 mg of crude reaction product is obtained. Chromatography on silica gel (0-20% ether:petroleum ether) provides 125 mg of the 3α-methyl compound and 234 mg of a slightly more polar mixture of 3β-methyl compounds (R* and S*).
NMR of 3α methyl component (300MHz, CDCl₃)δ 0.24 and 0.26 (2S, Si(CH₃)₂), 0.97 (S, Si-C(CH₃)₃), 1.22 (d, J=6Hz, CH₃CHOH-), 1.30 (S, CH₃), 2.34 (d, OH), 2.42-2.81 (m, CH₂CH=CH₂), 3.44 (dd, J=4 and 10Hg, H₄), 4.09 - 4.19 (m, CH₃CHOH-), 5.09-6.02 (m, -CH=CH₂).
NMR of 3β-methyl components (300MHz, CDCl₃)δ 0.23-0.25 (s's, Si(CH₃)₂'S), 0.95 and 0.96(2S, Si-C(CH₃)₃'S), 1.14 - 1.22 (series of peaks for CH₃'s and CH₃CHOH'S) 2.29 - 2.62 (m, CH₂CH=CH₂), 3.40 (dd, J=3.5 and llHz, _H4 of _S ^*), 3.70 (dd, J=3.5 and 11 Hz, H₄ of R^*), 3.86 - 4.00 (m, CH₃CHOH-), 5.08-5.96 (m, CH-CH₂).

1-(t-Butyldimethylsilyl)-3-(1-oxoethyl)-3β-methyl-4-(prop-2-en)-azetidin-2-one

Trifluoroacetic anhydride (180µl, 1.28 mmol) is added dropwise by syringe to a solution of dimethylsulfoxide (120µl, 1.69 mmol) in anhydrous methylene chloride (2.5 ml) at -78°C under N₂. The resulting mixture is stirred at -78°C for 15 min. A solution of 1-(t-butyldimethylsilyl)-3-(1-hydroxyethyl)-3β-methyl 4-(prop-2-en)-azetidin-2-one (234 mg, 0.83 mmol) in methylene chloride (2 ml) is added, and the resulting solution is stirred at -78°C for 1 hr. Triethylamine (382µl, 2.76 mmol) is added by syringe, and the cooling bath is removed. After an additional 1 hr, the reaction mixture is diluted with methylene chloride, washed with water and brine, dried over magnesium sulfate, filtered. Removal of solvents in vacuo yields partially crystalline oil. Chromatography on silica gel (0-10% ether:petroleum ether) provides 191 mg of the title compound. IR(CHCl₃)µ 5.76, 5.87 MS m/e NoM⁺, 266, 240, 224 NMR (60MHz, CDC13) 0.25(2S, Si(CH₃)₂), 0.97(s, SiC(CH₃)₃), 1.45(s, CH₃), 2.28(s, CH₃-C=0), 2.33-2.62 (m, CH₂CH=CH₂), 4.15(dd, J=5 and 10Hz, H₄), 4.88-6.10 (m, CH=CH₂).

1-(t-Butyldimethylsilyl)-3-(1-hydroxyethyl)-3β-methyl-4-(prop-2-en)-azetidin-2-one

To a stirred solution of 4.26g of 1-(t-butyldimethylsilyl)-3-(1-oxoethyl)-3β-methyl-4-(prop-2-en)-azetidin-2-one (15.2 mmol) in 90 ml i-propanol is added 807 mg sodium borohydride (21.2 mmol). After stirring vigorously under N₂ for 45 min, the reaction mixture is poured (carefully) into ~ 100ml 1M KH₂PO₄- 400 ml H₂O-500ml Et₂O. After phase separation, the aqueouslayer is washed 2 x Et₂O. The combined organic.layers are then washed 2 x brine, dried over magnesium sulfate, filtered, and concentrated in vacuo to 4.lg of an oil. Chromatography on 300g silica gel (0-10% acetone:hexane) provided 3.84g of material containing mainly the S* diastereomer and 1.58g of the R^* diastereomer. Data for the R^* diastereomer: IR(CHCl₃)µ 5.80 MS m/e 284(M⁺ + 1), 268, 226 NMR (300 MHz, CDCl₃) δ0.24 (2S, Si(CH₃)₂, 0.96(s, Si(CH₃)₃), 1.17(d, partially nidden by sat 1.18, CH₃CHOH-) 1.18 (s, CH₃)1 1,70(d, OH), 2.32-2.60 (m, CH₂CH=CH₂), 3.71(dd, J=4 and llHz, H₄), 3.89 - 3.98(m, CH₂CHOH), 5.12-5.90 (m, CH=CH₂).

1-(t-Butyldimethylsilyl)-3-(1-t-Butyldimethylsilyloxyethyl)-3β-methyl-4-(prop-2-en)-azetidin-2-one

With stirring under N₂, 582 mg of 1-(t-butyldimethylsilyl)-3-(1-hydroxyethyl)-3β-methyl-4-(prop-2-en)-azetidin-2-one (2.06 mmol) in 6 ml anhydrous N,N-dimethylformamide is treated with 320µl triethylamine (2.31 mmol) followed by 356 mg t-butyldimethylsilylchloride (2.37 mmol). After stirring over night, the reaction mixture is poured into 1.3 ml, 1MKH₂PO₄ ^- 50 ml brine-50 ml methylene chloride. After phase separation, the aqueous layer is again extracted with methylene chloride, The combined organic layers are washed 2 x brine, dried over magnesium sulfate, filtered and concentrated to 699 mg crude material. Chromatography on silica gel (0-50% ethylacetate:hexane) provides 473 mg of the title compound and 211 mg recovered starting material. IR (CHCl₃)µ 5.78 MS m/e 397 (M⁺), 382, 340 NMR (300MHz, CDCl₃)δ 0.05, 0.08, 0.21 and 0.26 (4S, Si(CH₃)₂'s), 0.90 and 0.96 (2S, Si-C(CH₃)₃'s), 1.11(d, J=6Hz, CH₃CHOSi-), 1.14(S, CH₃), 2.30-2.56 (m, CH₂CH=CH₂), 3.66(dd, J=4 and 10Hz, H₄), 3.91 (q, J=6Hz, CH CHOSi-), 5.03-5.94 (m, -CH=CH₂).

1-(t-Butyldimethylsily3)-3-(1-t-butyldimethylsilyloxyethyl)-3β-methyl-4-(2-oxoethyl)-azetidin-2-one

A solution of 1.05g (1-(t-butyldimethylsilyl)-3-(1-t-butyldimethylsilyloxyethyl)-3β-methyl-4-(prop-2-en)-azetidin-2-one (2.6 mmol) in 30 ml anhydrous methylene chloride is cooled to -78°C, and a stream of dried ozone in oxygen is bubbled through until the blue color disappears. The cooling bath is removed, and the reaction mixture is concentrated under a stream of N₂and then in vacuo. The crude. ozonide is dissolved in 5 ml methylene chloride and is treated with 580µl dimethylsulfide (7.9 mmol) and placed under N₂. After 6 hr, 580µl additional dimethylsulfide is added, and the reaction is allowed to stir overnight under N₂. The reaction is then concentrated under high vacuum followed by chromatography on silica gel (methylene chloride). Forward fractions, containing unreacted ozonide as well as the desired aldehyde, are re-treated with dimethylsulfide to increase the yield. Later fractions contain 531 mg of the desired aldehyde. IR(CHCl₃)µ 5.75, 5.80 (sh) M.S. m/e 400(M^t + 1), 384, 342 NMR (300 MHz, CDCl₃)δ 0.06, 0.09, 0.19 and 0.24 (4S, Si(CH₃)₂'s), 0.88 and 0.95 (2S, Si(CH₃)₃'s), 1.09(s, CH₃), 1.15(d, J=6Hz, CH₃CHOSi-), 2.75-2.80 (m, CH₂CHO), 3.98(q, J=6Hz, CH3CHOSi-), 4.16(dd, J=5.5 and 7.5 Hz, H₄), 9.84(t, CHO).

1_-(t-Butyldimethylsilyl)-3-(1-t-butyldimethylsilyloxyethyl)-3β-methyl-4-(carboxymethyl)-azetidin-2-one

A solution of 620 mg 1-(t-Butyldimethylsilyl)-3-(t-butyldimethylsilyloxyethyl)-3β-methyl-4-(2-oxoethyl)-azetidin-2-one (1.55 mmol) in 22 ml distilled acetone is cooled in an ice bath and treated with 447µl of Jones reagent (2.6M in CuO₃, 1.16 mmol). After stirring for 15 min., 409µl absolute ethanol is added, and stirring is continued for 5 min. The cooling bath is removed, and the reaction mixture is quickly concentrated under a N₂ stream to a small volume. Ethylacetate and water are added to the concentrate. After phase separation, the organic layer is washed 3 x brine, dried over magnesium sulfate, filtered, and concentrated to 629 mg crude product. Chromatography on silica gel (0-1% acetic acid:methylene chloride) provides 498 mg of the desired product. IR (CHCl₃)µ 5.76br M.S. m/e(silylated)- NoM⁺ at 487, 472, 430 (487-t-butyl) NMR (300MHz, CDCl₃)δ 0.04, 0.07, 0.20 and 0.24 (4S, Si(CH₃)₂'s), 0.86 and 0.93 (2s, Si-C(CH₃)₃'s), 1.09(d, J=6Hz, CH₃CHOSi), 1.11(s, CH₃), 2.63 and 2.72 (2dd, J=9 and 16Hz and J=5 and 16Hz respectively, CH₂CO₂H), 3.96(q, J=6Hz, CH₃CHOSi-), 4.11(dd, J=5 and 9Hz, H₄).

1-(t-Butyldimethylsilyl)-3-(1-t-Butyldimethylsilyloxyethyl)-3β-methyl-4-(3-p-nitrobenzyloxycarbonyl-2- oxopropyl)azetidin-2-one

1,1'-Carbonyldiimidazole (1.09mg, 0.67mmol) is added in one portion to a solution of 251 mg l-(t-butyldimethylsilyl)-3-(l-t-butyldimethylsilyloxyethyl)-3S-methyl-4-(carboxymethyl)-azetidin-2-one (0.60 mmol) in anhydrous tetrahydrofuran (3 ml) at room temperature under N₂. The resulting solution is stirred at room temperature for 3.5 hours. In a second flask, magnesium ethoxide (5 mmol) is added in one portion to a solution of the mono-p-nitrobenzyl ester of malonic acid (10 mmol) in anhydrous tetrahydrofuran (25 ml). The resulting mixture is stirred at room temperature for 1 hr, then the tetrahydrofuran is removed at the pump, and the gummy residue is triturated with ether to yield the magnesium salt as an off-white solid. The magnesium salt (339 mg, 0.678 mmol) is then added to the first reaction flask and the resulting mixture is stirred at room temperature overnight. The reaction mixture is then poured into 50 ml of ether, washed with 0.5N hydrochloric acid solution (12.3 ml), water (12.3 ml), saturated aqueous sodium bicarbonate solution (12.3 ml), brine and dried over magnesium sulfate. Removal of solvents in vacuo gives 356mg of an oil which is chromatographed on 6-1000µ silica gel GF plates (25% acetone/hexanel. The desired UV band is immediately scraped and extracted with 70% acetone/hexane. Concentration in vacuo gives 235 mg of the title compound. IR(CHCl₃)µ 5.75 M.S. m/e NoM⁺ at 592, 577, 535 (M⁺-t-butyl) NMR (300MHz, CDCl₃) δ 0.04, 0.08, 0.15 and 0.20 (4S, Si(CH₃)₂'s), 0.86 and 0.92 (2S, Si-C(CH₃)₃'s), 1.02 (s, CH₃), 1.12 (d, J=6Hz, CH₃CHOSi-) 2.87 (brd, J=6Hz, CH₂C-CH₂CO₂-), 3.58 (S, C-CH₂CO₂-), 3.95(q, J=6Hz, CH₃CHOSi-), 4.17(brt, J=6Hz, H₄) 5.29 (s, CO₂CH₂φpNO₂), 7.56 and 8.27 (2d, aromatic protons).

3-(1-hydroxyethyl)-3β-methyl-4-(3-p-nitrobenzyloxycarbonyl-2-oxopropyl)azetidin-2-one

Concentrated hydrochloric acid (0.68 ml) is brought to a volume of 40 ml with 9:1 methanol:water, and 22ml of the solution (4.5 mmol) is added to 319 mg of 1-(t-butyldimethylsilyl)-3β(1-t-butyldimethylsilyloxyethyl)-3β-methyl-4-(3-p-nitrobenzyloxycarbonyl-2-oxopropyl)-azetidin-2-one (0.54 mmol) with good stirring under N₂. After 8 hr, the reaction is added to 8 ml 1MK₂HPO₄- 150 ml H₂0 - 150 ml ethylacetate. After phase separtion, the organic layer is washed with brine containing 8 ml 1MK₂HPO₄ and then brine alone (2x). After drying over magnesium sulfate, filtration, and concentration in vacuo, 241 mg of an oil is obtained. Chromatography on 6-1000µ silica gel GF plates (50% acetone/hexane) followed by extraction of the desired UV band with 70% acetone/hexane provides 129 mg of the title compound. A less polar UV band contains 57 mg of material still having the 0-silyl group intact.
Data for the compound: IR(CHCl₃)µ 5.70(br), 5.81(sh) M.S. m/e NMR(300MHz, CDCl₃)δ 1.14 (s, CH₃), 1.23 (d, J=6Hz, CH3CHOH), 2.81-2.98 (m, CH₂CH₂CO₂-) , 3.62 (s, CH₂CO₂-CH₂φPNO₂), 4.05(center of m, H₄ and CH₃CHOH), 5.30 (s, CO₂CH₂φpNO₂), 6.01(br, s, NH), 7.57 and 8.30 (2d, aromatics).

3-(1-Hydroxyethyl)-3β-methyl-4-(3-diazo-3-p-nitrobenzyloxycarbonyl-2-oxopropyl)-azetidin-2-one

Triethylamine (55µl, 0.397 mmol) is added by syringe to a mixture of 3-(1-hydroxyethyl)-3β-methyl-4-[3-(p-nitrobenzyl)oxycarbonyl-2-oxopropyl]-azetidin-2-one (40 mg, 0.11 mmol) and p-carboxybenzene sulfonylazide (30 mg, 0.13 mmol) in dry acetonitrile (1 ml) at 0°C. When addition is complete, the cooling bath is removed, and the reaction mixture is stirred at room temperature for 1.5 hour. The mixture is then diluted with ethyl acetate (10 ml) and filtered. The filtrate is concentrated in vacuo, and the residue is dissolved in methylene chloride, filtered, and concentrated in vacuo to 53 mg white foam. A fast filtration through a short silica gel column (ethylacetate) provides 41 mg of the title compound as a slightly off white solid. On a larger scale, the product may crystallize out of the reaction mixture along with by-products of the reaction. Extraction of the original, insoluble materials with methylene chloride, followed by chromatography of the contents of the filtrate, yields the product in these instances. mp 162-170°C dec. IR(CHCl₃)µ 4.70, 5.70, 5.81 _NMR (300_MHz, di-DMSO)δ 0.95 (s, CH₃), 1.03(d, J=6Hz, CH₃CHOH), 3.05 (d, J=6Hz, CH₂CCH₂CO₂-), 3.68-3.76 (m, CH₃CHOH), 3.90(t, J=6Hz, H₄), 4.85(d, OH), 5.46(s, CH₂-φ-p-NO₂), 7.76 and 8.31(2d, aromatic protons), 7.93 (s, NH).

p-Nitrobenzyl 6-(1-hydroxyethyl)-6β-methyl-3-[2-p-nitrobenzyloxycarbonyl)aminolethylthio-1-azabicyclo-[3.2.0]hept-2-en-7-one-2-carboxylate

A suspension of 3-(1-hydroxyethyl)-3β-methyl-4-[3-diazo-3-p-nitrobenzyloxycarbonyl-2-oxopropyl]-azetidin-2_-one (35 mg, 0.09 mmol) and rhodium (II) acetate (0.1 mg) in dry toluene (3.2 ml) is deoxygenated by evacuating and treating with nitrogen alternately (3X). The mixture is then heated to ca. 100°C for 1 hour with stirring under N₂. During heating the solid starting material gradually goes into solution. The mixture is then cooled, filtered to remove the catalyst, and the filtrate is concentrated in vacuo to yield the above bicycloketone as a white foam. The crude bicycloketone (32.5 mg, 0.09 mmol) is dissolved in anhydrous acetonitrile (1.8 ml), and the resulting solution is cooled to 0°C under N₂. Diisopropylethylamine (18.9µl, 0.11 mmol) is added followed by diphenylchlorophosphate (19.9µl, 0.10 mmol), and the resulting solution is stirred at 0°C for 55 min. Diisopropylethylamine (17.7µl, 0.10 mmol) is added by syringe followed by p-nitrobenzyloxycarbonylaminoethanethiol (26.6 mg, 0.104 mmol), and the reaction is stirred for 2.5 hr. The reaction is then added to 20 ml ethylacetate-10 ml water. After separation of the layers, the organic layer is extracted with 8 ml 0.1M KH₂P0₄, 8ml 0.lM K₂HP0₄, 2xbrine, dried over magnesium sulfate, filtered and concentrated in vacuo to 65 mg yellow foam. Chromatography on 3-1000µ silica gel GF plates (ethylacetate) provides upon extraction (ethylacetate)of the desired UV band, concentration to an oil, addition of methylene chloride (drying over magnesium sulfate), filtration, and reconcentration in vacuo, 31 mg of the title compound as a pale yellow foam. IR (CHCl₃)µ 5.64, 5.81(br) M.S. m/e 600 (M⁺), 556, 301 NMR (300MHz, CDCl₃) δ 1.24 (S, CH3), 1.27(d, J=6_Hz, CH₃CHOH), 3.15 (d for H's with J=9Hz on top of m from 2.94-3.2 for -SCH₂CH₂NH-), 3.39 - 3.52 (m, -SCH₂CH₂-NH-), 4.15(center of m, CH₃CHOH), 4.31 (brt, J=9Hz, H₅), 5.20 (s, NHCO₂CH₂ arom), 5.38(center of two widely spaced d, noneq. methylene protons of ester), 7.50-8.27 (series of peaks, aromatics).

(+)-6-methylthienamycin

To 5.3mg p-nitrobenzyl 6-(1-hydroxyethyl)-6β-methyl-3-[2-p-nitrobenzyloxycarbonyl)amino]ethylthio-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate is added 500µl distilled THF, 500µl absolute EtOH, 330µl DI-water, 33µl MOPS buffer, 6.9mg platinum oxide, and two glass beads. The reaction mixture is placed in a Parr shaker, evacuated and covered with N₂ alternately (3X), evacuated and covered with 50psi H₂. After cooling in an ice bath, the reaction mixture is centrifuged, and the supernatant is filtered through a small plug of cotton into a cold centrifuge tube. The residual catalyst is washed (3X) with 15 drops DI-H₂0 and centrifuged; the supernatants are added to the original filtrate which is finally extracted with ethylacetate (3 x 1 ml). The aqueous layer is briefly placed on an aspirator to remove residual organic solvents and then applied to a small column of XAD-2 resin (~7ml vol) packed and eluted with DI-H₂0. After the first 2.5 ml, the next 30 ml eluant contains the product. The above sequence is repeated on 5.4mg and 5.0 mg additional starting material.
The combined aqueous solutions are concentrated in vacuo without heat to 3 ml volume. The solution is passed portionwise through a semi-prep (9.5ml void volume) µ-Bondapak-C₁₈ HPLC column (3% THF/DI-H₂0, flow rate-2 ml/min, 254mµ filter), and the major peak is collected. Concentration, as above, afforded a soltuion of 2.1mg of the title compound having a hydroxylamine-quenchable UV_max at 297mµ, essentially no electrophoretics mobility in pH7 phosphate buffer (1500V-30 min), and a clean HPLC trace (retention time ~ 6.5 min).

EXAMPLE 14

Following the procedure of Example 2, the azetidinones of Table I are obtained when the basic procedure of Example 2 is modified according to the remarks entered in Table I.

EXAMPLE 15

Following the foregoing Examples and text, particularly Example 9, the representative intermediates of the present invention are obtained when the indicated substitution from Example 14 is made into the scheme of Example 9.

Incorporation by Reference

The final antibiotic compounds of the present invention Structure I:
wherein _R ⁶, _R ⁷ and R⁸ are defined above are fully disclosed and claimed in co-pending European Patent Application Serial Number 80 102 076 filed April 18, 1980; thus, to the extent that this co-pending U.S. Patent Application defines the compounds of Structure I, their synthesis and their utility as antibiotics, it is incorporated herein by reference.
The compounds of the present invention may also be prepared by the processes disclosed and claimed in the three (3) following, co-pending, commonly assigned U.S. Patent Applications of Christensen, Ratcliffe and Salzmann. To the extent that these applications define R⁶, R⁷, and R⁸ of Structure _I and to the extent that they describe processes for the synthesis of intermediates III and IV (defined above) they are hereby incorporated by reference.
wherein R⁶, R⁷ and X are defined above.

1.) Process for the Preparation of 1-Carbapenems and Intermediates via 4-Allylazetidinone; U.S. Patent Application Serial Number , filed 3-27-80 [Merck & Co., Inc. Attorney's Docket Case 16479].
2.) Process for the Preparation of 1-Carbapenems and Intermediates via Trithioorthoacetates; U.S. Patent Application Serail Number , filed 3-27-80 [Merck & Co., Inc. Attorney's Docket Case 16485].
3.) Process for the Preparation of 1-Carbapenems and Intermediates via Silyl-Substituted Dithioacetals; U.S. Patent Application Serial Number filed 3-27-80 [Merck & Co., Inc. Attorney's Docket Case 16478].

Also incorporated by reference is published European Patent Application 0007614 (Application Number 79102615.6, filed 24 July 1979). This application discloses certain dipeptidase inhibitors which, on co-administration to mammalian subjects, enhance the efficacy of certain 1-carbadethiapenem antibiotics. Thus, to the extent that the cited application: l.)defines the manner by which susceptible carbadethiapenems substrates of the present invention may be identified; and 2.) discloses suitable inhibitors, compositions, and methods of treatment, it is incorporated herein by reference. A particularly preferred inhibitor is 6-(L-2-Amino-2-carboxyethylthio)-2-(2,2-DCC)-2-hexenoic acid.
Intermediates IV wherein X is halo are conveniently prepared from intermediates III by the procedures disclosed in co-pending, commonly assigned U.S. Patent Application Serial Number 26,979 filed April 4, 1979, which is incorporated herein by reference.

Claims

1. A process for preparing a compound having the structural formula:

and the pharmaceuticaliy acceptable salt ester and amide derivatives thereof; wherein R⁶, R and R⁸ are independently selected from the group consisting of: hydrogen; substituted and unsubstituted: alkyl, alkenyl, and alkynyl, having from 1-10 carbon atoms; cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties; phenyl, aralkyl, aralkenyl, and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms; heteroaryl, heteroaralkyl, heterocyclyl and heterocyclylalkyl; wherein the substituent or substituents relative to the above-named radicals are selected from the group consisting of: chloro, bromo, fluoro, _R ¹,

wherein, relative to the above listed substituents on R⁶, R⁷ and R⁸, the groups R¹ and R² are independently selected from: hydrogen, alkyl, alkenyl, and alkynyl, having from 1-10 carbon atoms; cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties; phenyl; aralkyl, aralkenyl, and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms; heteroaryl, heteroaralkyl, heterocyclyl and heterocyclylalkyl; and wherein the hetero atom or atoms in the above-named heterocyclic moieties are selected from the group consisting of 1-4 oxygen, nitrogen or sulphur atoms and wherein the alkyl moieties associated with said heterocyclic moieties have 1-6 carbon atoms; comprising activating and treating with HSR⁸ a compound of the structure:

wherein R³ is a protecting group or a pharmaceutically acceptable ester moiety; when R⁶/R⁷ is hydrogen and R⁷/R⁶ is CH₃CH(OH), then R⁸ is not -CH₂CH₂NH₂.

2. A process according to Claim 1 comprising treating:

with HSR⁸ wherein X is a leaving group.

3. A compound selected from:

wherein X is a leaving group, R³ is hydrogen, a salt cation, a protecting group, or a pharmaceutically acceptable ester moiety; and wherein R⁶, _R ⁷ and R⁸ are independently selected from the group consisting of: hydrogen; substituted and unsubstituted: alkyl, alkenyl, and alkynyl, having from 1-10 carbon atoms; cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties; phenyl, aralkyl, aralkenyl, and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms; heteroaryl, heteroaralkyl, heterocyclyl and heterocyclylalkyl; wherein the substituent or substituents relative to the above-named radicals are selected from the group consisting of: chloro, bromo, fluoro, R¹,

wherein, relative to the above listed substituents on _R ⁶, R and R⁸, the groups R¹ and R²are independently selected from: hydrogen, alkyl, alkenyl, and alkynyl, having from 1-10 carbon atoms; cycloalkyl, cycloalkylalkyl, and alkylcycloalkyl, having 3-6 carbon atoms in the cycloalkyl ring and 1-6 carbon atoms in the alkyl moieties; phenyl; aralkyl, aralkenyl, and aralkynyl wherein the aryl moiety is phenyl and the aliphatic portion has 1-6 carbon atoms; heteroaryl, heteroaralkyl, heterocyclyl and heterocyclylalkyl; and wherein the hetero atom or atoms in the above-named heterocyclic moieties are selected from the group consisting of 1-4 oxygen, nitrogen or sulphur atoms and wherein the alkyl moieties associated with said heterocyclic moieties have 1-6 carbon atoms; when R⁶/R⁷ is hydrogen, then R⁷/R⁶ is not CH₃CH(OH).

4. A compound according to Claim 3, wherein R⁷ is selected from H, OCH₃ and CH₃.

5. A compound according to Claim 4 wherein R⁶ is selected from the group consisting of: substituted and unsubstituted: alkyl, alkenyl and cycloalkylalkyl wherein the substituent or substituents are selected from hydroxyl, alkoxyl having from 1-6 carbon atoms, phenoxy, amino, and carboxy.

6. A compound according to Claims 4 or 5 wherein R⁶ is selected from the group consisting of alkyl, cycloalkylalkyl, alkyl substituted by one or more hydroxyl groups, or cycloalkylalkyl substituted by one or more hydroxyl groups.

7. A compound according to Claims 4, 5 or 6 wherein R⁷ is hydrogen.

8. A compound according to Claims 3, 4, 5, 6, or 7 wherein R6 is selected from:

φ = phenyl

9. A compound according to Claim 3 wherein X is chloro, bromo, iodo, phenylsulfonyloxy, p-toluylsulfonyloxy, p-nitrophenylsulfonyloxy, methylsulfonyloxy, trifluoromethylsulfonyloxy, diphenylphosphoryl, bis(trichloroethyl)phosphoryl.

10. A compound according to Claims 3, 4 or 7 selected from: H,

wherein: y = 0 or 1; X = OH, NH₂; SH; n 0 or 1; R = substituted or unsubstituted: alkyl, alkenyl or alkynyl having 1-6 carbon atoms wherein the substituent is R¹; R^1° = alkoxyl, carboxyl, CF₃, OH, H, linear or branched alkyl bearing 1 or more hydroxyl groups, amino, aminoalkyl, Cl, F, Br, alkylthio, amidino, guanidino, oximino, phenyloxy, phenylthio,

11. A process according to Claims 1 or 2 wherein R⁸ is selected from:

1.) aliphatic (including carbocyclic) groups having 1-10 carbon atoms selected from: alkyl, cycloalkyl, alkenyl, cycloalkenyl and alkynyl;

2.) substituted aliphatic groups having 1-10 carbon atoms selected from: alkyl, cycloalkyl, alkenyl, cycloalkenyl and alkynyl; wherein the substituents are selected from: chloro, bromo, fluoro, R¹,

3.) aryl and substituted aryl; wherein the aryl is phenyl and wherein the substituents are defined above under 2.);

4.) heteroaryl and substituted heteroaryl having 1-4 O, N or S atoms; and wherein the substituents are defined above under 2.);

5.) arylaliphatic, wherein aryl is phenyl, which are selected from the aliphatic groups defined under 1.) which are substituted by phenyl or substituted phenyl; wherein such substituents on phenyl are defined under 2.), above;

6.) heteroarylaliphatic and heterocyclylaliphatic; wherein the aliphatic moiety is defined under 1.), above; the substituted and unsubstituted heteroaryl and heterocyclic moieties have 1-4 O, N or S atoms; wherein such substituents are defined under 2.),above;

7.) substituted and unsubstituted alkyl-heteroatom-alkyl having 4-12 carbon atoms; wherein the heteroatom is selected from: O, S, NR° (R° is H, substituted or unsubstituted alkyl); wherein such substituents are defined under 2.),above.

12. A process according to Claim 11, subparagraph 1.); wherein R⁸ is selected from: